Comparing "lijie" and "liaojie"

理解 and 了解 both mean “understand” or “comprehend” a person or the way something is. Yet, both have distinct meanings, for example 理解 means after much thought and deliberation to grasp an understanding of a principle, a reason, material, a person’s deep inner thoughts or feelings, and 了解 means “to know about”, “to know of”, “to think about” a person or concept. As well, 了解 can mean “to get to know” or “to find out about” or “to become aware of how something will work out“

	理解 (lǐjiě)	了解 (liǎojiě)
Meaning	to understand deeply	to know about, to know of
Part of Speech	verb	verb
Formality	formal	flexible

Similarities:

Parts of Speech: both are verbs.

Meaning: Both mean “understand” or “comprehend” a person or the way something is.

Collocations: These patterns work with both 理解 and 了解：很～你, 不～你, 不太～, 互相～,

   Example sentences ( 理解 AND 了解 both can be used):

一 二 三 四

Differences:

Formal/Informal: 理解 is used much more often in formal settings and written Chinese, whereas 了解 is used both in formal/informal settings and written/spoken Chinese.

Meaning: 理解 means after much thought and deliberation “to grasp an understanding of ” a principle, a reason, material, a person’s deep inner thoughts or feelings.

Collocations: These patterns work only with 理解：不能～, ～不了, ～力, ～错了, 表示～

Example sentences (only 理解 can be used): 一 二 三 四

Meaning: 了解 means “to know about”, “to know of”, “to think about” a person or concept.

Example sentences (only 了解 can be used): 一 二 三 四

Meaning: 了解 means “to get to know” or “to find out about” “to become aware of how something will work out“ (think “ahh… got you!”) of a condition or a situation.

Collocations: These patterns work only with 了解：～情况, ～一下, 了解了解

Example sentences (only 了解 can be used): 一 二 三 四